Characteristics of Spark Discharges from Vehicles Energized by AC Electric Fields

This study examined certain characteristics of spark discharges from vehicles energized by an electric field. Vehicles were placed in an electric field produced by a 500 kV transmission line. Spark discharges were delivered through a resistor to a driven ground rod. Discharge current and voltage were monitored. These data are analyzed to determine capacitance measured under transient spark conditions and are compared with capacitance determined from 60 Hz measurements. The importance of the vehicle tires is examined. Spark discharge waveforms were also studied using standard high-voltage capacitors for comparison with those discharge waveforms obtained from measurements on the vehicles. The influence of the impedance of the earth return is discussed with reference to differences between the waveforms from the vehicles and the laboratory capacitors.